1. Field of the Invention
The present invention is directed to an arrangement for data processing and more particularly to an arrangement for data processing in transcoder units of mobile radiotelephone systems.
2. Description of the Prior Art
The cellular mobile radiotelephone system GSM (Global System for Mobile Communication) is an example of a digital mobile radiotelephone system. The multiple access method TDMA (Time-Division Multiple Access) is used in this system, whereby mobile stations are distinguished from one another by different time slots of a time-division multiplex system.
FIG. 1 shows a block circuit diagram of such a mobile radiotelephone system 10 whose coverage area is divided into a number of cells. A telecommunication service from and to a mobile stations MS in a cell is offered by a base station BS. One or more base stations BS are connected to a base station controller BSC. The base station controller BSC implements the local functions of call switching, monitoring and maintenance. A number of base station controllers BSC are connected to a switching center MSC.
Given a transmission of voice to or from a mobile station MS, it is notoriously known to sample analog voice information at the transmission side and to convert the sampled analog voice information into digitally encoded voice information in a voice encoder and to transmit this digitally encoded voice information error-protected as warranted. At the reception side, the digitally encoded voice information is then converted into analog voice information.
In the aforementioned GSM mobile radiotelephone system 10, which only serves below to illustrate the technological background of the invention without limiting the universality of its employment, the transcoder unit TRAU (Transcoding and Rate Adaptation unit) implements the adaptation of the data rate that is communicated from a telephone network PSTN to the data rate defined in the mobile radiotelephone system.
The transcoder unit must implement the encoding for a number of channels and is modularly constructed as an arrangement for data processing. A number of data processors implement the encoding and rate adaptation in parallel, whereby individual memories keep the program code for the encoding on hand. For 120 channels, for example, this means that the program code is stored 120 times per transcoder unit. The arrangement for data processing therefore requires a great number of memories, each incurring corresponding costs.
Further, when various encoding methods are employed, the corresponding program code must additionally be stored for each encoding method.
An object of the present invention is to provide an arrangement for data processing wherein the memory requirement is reduced.
A number of digital data processors that each contain at least one processor, a memory, and an interface are provided in the inventive arrangement for data processing. Further, the arrangement employs at least one digital transmitter that is connected to the data processors via a program bus and sends program code, of which only parts are stored in a respective data processors, over the program bus.
A continuous transmission of program code assures that the program parts required at the moment and that are used for the data processing are always present in the data processors even without continuous storage of the entire program code. These program parts can be individually received and stored in each of the data processors. The memory requirement, thus, is reduced according to the functions to be implemented at the time, since program parts that are not required can be overwritten.
The transmission of the program code makes it possible to connect to a number of data processors that are not limited in advance to the program bus. This simplifies the subsequent upgrading of the arrangement for data processing. The introduction of new programs is also facilitated by the inventive arrangement since the data processors are always prepared for a software update.
In an exemplary embodiment of the invention, the memory advantageously employs both a program memory and a data memory. As a result of separating program memory, which stores the program parts received by the interface, and data memory, the data processing can be implemented separately from the updating of program code. The overall arrangement for data processing becomes more flexible as a result thereof.
In a further exemplary embodiment of the invention, the data processors are advantageously configured as digital signal processors. The inventive arrangement reduces the cost problems typically associated with the parallel processing of large datasets in signal processing, by requiring less memories. When the data processing relates to an encoding/decoding or rate adaptation that is subject to constant modifications as in, for example, adaptive multi-rate encoders, then the transmission of the program code and the need-suited reception effects further essential savings. The invention, however, can also be employed in other data processing equipment.
According to this exemplary embodiment of the invention, when the digital data processors undertake connection-related encoding or decoding, then individual adaptations of the program code for each and every individual data processor are possible, which permits the saving of memory space. Memory space can be saved, for example, in transcoder units in mobile radiotelephone systems that process a number of data channels in parallel and individually.
In a further exemplary embodiment of the invention, the data rate of the program code transmission is set to a frame structure of a parallel information transmission. Since new algorithms are not needed at random points in time but at points in time to be predicted according to the frame structure, a correspondingly high data rate of the program code transmission assures that every potentially required part of the program code can be loaded within a cycle of the frame structure or a multiple thereof.
In a further exemplary embodiment of the invention, the storing of the various parts of the program code initiates either a connection-related encoding method for updating of a program structure or a connection-related switching between encoding methods. The program code is thus not stored in reserve but only in preparation for a modification of the current data processing.